A recent study by the U.S. International Trade Commission indicates that counterfeiting of name brand goods is presently costing American businesses up to eight billion dollars in lost sales annually. In addition, the counterfeiting is effectively costing the work force some 131,000 jobs per year. Still more startling is the fact that the counterfeiting menance is increasing. The growth of counterfeiting, however, should be easy to understand when the huge profits obtainable by the counterfeiter on the sale of low quality, bogus goods at name brand prices are considered.
In order to combat the counterfeiting problem, technologies have been developed for placing an identifiable marker or tag on the name brand goods. Of course, the markers themselves must be made very difficult to counterfeit in order to be effective. Typically, the marking system is designed so that at least the cost of breaking the code and reproducing the marker or tag is prohibitive to the counterfeiter. However, on the other hand, the markers and the identifying system must be produced at a relatively low cost so as to make the concept economically feasible to the brand name manufacturer seeking to protect its products.
An example of a tagging or marking system is found in copending U.S. patent application Ser. No. 373,061 filed Apr. 29, 1982 now U.S. Pat. No. 4,510,489, entitled "Surveillance System Having Magnetomechanical Marker" and assigned to Allied Corporation, the assignee of the present invention. The marker preferably includes an amorphous metal strip of ferromagnetic material adapted to be magnetically biased and thereby armed to resonate mechanically at a frequency within the frequency band of a magnetic interrogation field.
As shown in the copending application, markers of this kind are presently used in theft detection systems. A transmitting apparatus including a drive coil is situated on one side of a passageway leading to an exit from the premises. A receiving apparatus including a receive coil is positioned at the opposite side of the passageway. The drive coil sweeps through a predefined spectrum of frequencies including the resonant frequency of the target ribbon of the marker.
As the drive frequency passes through the resonant frequency of the marker ribbon, the marker generates a distinctive increase in the voltage induced in the receive coil. This marked effect upon the fundamental frequency voltage induced in the receive coil allows simple and accurate marker detection even in the presence of other objects. Of course, detection indicates that the marker has not been properly deactivated or removed from the marked article by the cashier.
In such a theft detection system, the drive and receive coils of the antenna are spaced apart the width of the passageway, possibly as much as six feet (6'). Thus, the interrogation zone defined between the drive and receive coils is quite large. The drive coil must, therefore, be adapted to apply a wide, strong magnetic interrogation field in order to energize and detect targets in the passageway leading to the exit. This system is not, however, well adapted for checking articles at close range for authenticity or the like.
Thus, a need is identified for a scanning unit capable of energizing and reading markers only at a very short range and within a very narrow zone. A hand held battery powered unit with this capability is desired for on site product verification at any distribution or retail location.
Further, if target markers of this type are to be successfully adapted for product verification, it is desirable to have a larger number of different marker codes available to prevent or discourage counterfeiting of the markers. One way we have discovered to do this is mentioned in copending U.S. patent application Ser. No. 384,814, filed June 3, 1982 now U.S. Pat. No. 4,510,490, for coded surveillance system having magnetic mechanical marker. This includes the use of markers including multiple amorphous ribbons; each ribbon being designed to resonate mechanically in response to the interrogation field at a different identifiable frequency. However, where a wide range drive coil is used to interrogate the markers as in the prior art, only the presence of the different frequency ribbons (in no particular sequence) may be determined. We have found there is no previously-known way to accurately determine the order or sequence of the ribbons in the marker.
A short range, narrow zone scanning unit has been developed to solve the problem. With the scanning unit contemplated by us, the number of marker codes can be greatly increased as the multiple ribbons may be lined up side-by-side and read in sequence. Where original manufactured articles are properly marked, any variation in the one or more frequencies present, or in the order of the frequencies, indicates that the marked article is a counterfeit.
Of course, such a scanning unit also has ready application to other security devices wherein an increased number of codes is desirable, such as in card reading devices, remote control locks, article surveillance devices, and personal identification systems.